The present invention relates to a drum-type sorting machine, particularly for domestic refuse and for commercial refuse having a composition approximating that of domestic refuse.
More particularly, the invention relates to a drum-type sorting machine which is provided with built-in refuse comminuting devices.
Generally speaking, screen-type machines are capable only of producing a classification but not a sorting of mixes of materials. Vol. 1, "Material Recycling aus Haushaltsabfall", Prof. Dipl.-Ing. Bernhard Jaeger and Prof. Dr.-Ing. K.J. Thoma-Kozmiensky, pp 254-274. Only the selected size reduction of individual types of materials within the material mix permits certain sorting processes to be carried out with a screen-type machine.
Furthermore, a classification for classifying sorting of refuse mixtures requires a preliminary partial size reduction (i.e. comminution) of compressed refuse cubes, filled paper and plastic bags or the like. This size reduction heretofore has always required a separate operating step.
All screen-type machines used for these purposes, including drum-type screen machines for processes of household refuse, tend to become clogged by the exceptionally heterogeneous material to be processed. To clean drum-type screen machines it is known to provide rotating brush rollers which continuously brush against the inner circumferential surface and/or the outer circumferential surface of the drum to brush off adhering material. Ibid., p 263. Drum cleaning devices of this type heretofore could be used only with relatively small drum sizes and relatively small screen openings. In the screen drum constructions which have been known in the art heretofore, in which the length of the drum is a multiple of its diameter, drums having a length of between about 8-12 meters are needed if significant amounts of material are to be processed per unit of time. In this type of construction it is, of course, not possible to have a shaft extend through the interior of the drum with brushes on it to brush the inside surface of the drum, because the shaft cannot be supported within the confines of the drum and over such a great length tends to oscillate uncontrollably. Moreover, shaft-mounted rotary cleaning brushes can only be used for pre-comminuted refuse and in conjunction with relatively small screen openings, because in the event of non-comminuted refuse or only partially comminuted refuse, larger textile scraps or pieces of synthetic plastic foil would become round around the rotary brush and prevent the same from proper operation.